Ignore the scare tactics! If you've decided to learn Czech, the first thing that other learners or (especially) natives may do is tell you how hard it is. It's got 7 cases, unpronounceable consonant clusters, irregular plurals, unrecognisable vocabulary, the hard-to-pronounce letter Å, lions and tigers and bears, oh my!!!
Definition of villainous. 1a : befitting a villain (as in evil or depraved character) a villainous attackb : being or having the character of a villain : depraved the villainous foe.
Alternatively, the character may already be evil, but the Hero's intervention results in the villain gaining superpowers, and a super-grudge to boot. In a parody or deconstruction of this trope, it might go on to reveal that the actions of the hero were actually irrelevant in terms of the individual's true nature.